Good Question: Why Are Bugs Attracted To Light?

MINNEAPOLIS (WCCO) — We all know that bugs are even worse at night when the street lamps come on or the front porch light. So why are bugs attracted to light?

“It’s kind of complicated, but bugs need a little bit of light in order to navigate. They need fixed light points,” said Mike McLean of the Metropolitan Mosquito Control District.

McLean said before artificial light came around, bugs used the stars and the moon to help them with navigation. When we turn on a light now, we are essentially turning on an artificial moon that really confuses our little friends- who are just trying to migrate or search for food.

“We’ve created a lot of artificial moons out there in the evening. And you can see the insects try to compensate like crazy,” said McLean.

Moths get really confused. They perceive the light as stronger in one eye than the other. That causes one wing to beat faster so they fly in a circle. McLean’s office uses light to trap mosquitoes. It’s called a CDC trap.

“It will confuse them and they will get a little closer and then there is a fan that will blow them down into this bag,” said McLean.

Nearly all insects are attracted to some form of light. It’s called phototaxis. But light also keeps some unwanted pests away.

“Some insects, like cockroaches, are negatively phototactic and they will scurry away when the light comes on,” said McLean.

McLean added that mosquitoes are attracted to light in a certain spectrum.

Insects like UV light, but don’t pick up on yellow or red lights. So, a lot of people put yellow lights on their front porch to keep bugs away.